While we manage all aspects of primary eye care, what sets us apart as a profession is managing cornea and external disease. Fortunately, the cornea requires little extra equipment beyond our slit lamp to visualize pathology effectively. Consider the opportunities ranging from dry eye disease, epithelial basement membrane dystrophy/recurrent corneal erosion and Fuchs’ dystrophy to keratoconus, abrasions, foreign bodies and numerous forms of keratitis—just to name a few!
Dry Eye Disease
It’s essential to differentiate the type of dry eye first; otherwise, your treatment strategy isn’t likely to work. Expression of the meibomian glands can be done in two to five seconds with an expression paddle. Abnormal expression will indicate an evaporative dry eye. In contrast, normal meibomian gland expression with significant corneal staining (using NaFl dye) and a thin meniscus will indicate an aqueous-deficient dry eye. Keep in mind that the location of the stain is critical—inferior stain will indicate incomplete overnight lid closure or potentially lagophthalmos.
NaFI dye will also aid in the visualization of a foreign body, papillae, conjunctival staining, conjunctivochalasis, limbal stem cell deficiency, persistent epithelial corneal defects, abrasions and corneal ulcers.
Corneal Foreign Body Removal
When managing corneal foreign bodies, begin with visual acuity testing followed by a slit lamp examination and determine the location, depth and possible material you are dealing with. Rule out an infiltrative process in the cornea indicative of a secondary infection. Observe the anterior chamber for cell and flare. Next, place NaFl dye in the eye to help find the foreign body and always evert the upper eyelid.
Determining the depth is critical and using a slit beam will help you see how far into the cornea it has penetrated. If there is no risk of intraocular foreign bodies, intraocular pressure assessment will confirm and you can begin working on removal. Consider using a 30-gauge needle—which is beveled—and keep the bevel toward the cornea to lift the foreign bodies (sterile jeweler’s forceps can also be used). This is especially helpful for a metallic foreign body. Be sure to remove significant residual rust in the cornea with an Alger brush. An antibiotic drop should be instilled and prescribed until the epithelium is healed. Corticosteroids may need to be considered after re-epithelialization if significant inflammation and/or an anterior chamber reaction is noted.
The Evolution of Crosslinking
There are two potential future treatments. The first involves a scleral lens with a built-in transducer that emits UV light. The scleral lens bowl is filled with riboflavin solution and placed on the cornea, and the patient wears the lens, which is hooked up to a machine that administers the light treatments.
The second, soon to enter Phase III FDA clinical studies, involves lysyl oxidase, a substance that is deficient in patients with keratoconus. Phase IIb trials with drops containing this ingredient show a decrease of 1.8D in K values, which is technically a greater response than currently approved corneal crosslinking options.
Herpes Zoster Ophthalmics (HZO)
Optometry is seeing more of these cases and we have to be prepared to manage these patients. Although the cornea is heavily involved, with signs ranging from pseudodendrites to eventual neurotrophic keratitis and lipid keratopathy, the most common sign of HZO is iritis. Since this is a systemic disease with ocular manifestations, the primary therapy is oral antivirals. I prefer valacyclovir 1000mg three times a day for 10 to 14 days.
Additionally, treat the ocular inflammation early with potent topical steroids to prevent corneal scarring and quiet the uveitis. Tapering can occur over six weeks and you may need to maintain a prophylactic dose of oral valacyclovir of 1000mg once a day. Also consider ophthalmic gel Zirgan (Bausch + Lomb) five times per day for a week followed by three times a day for a week when the cornea is involved. This aggressive management will help spare vision loss.
The cornea is a comfortable place for optometry. Keep your skills up and gain confidence as you work on a structure that is readily visible and will make a difference for you and your patients in this cornerstone of optometric care.
Dr. Karpecki is medical director for Keplr Vision and the Dry Eye Institutes of Kentucky and Indiana. He is the Chief Clinical Editor for Review of Optometry and chair of the New Technologies & Treatments conferences. A fixture in optometric clinical education, he consults for a wide array of ophthalmic clients, including ones discussed in this article. Dr. Karpecki's full list of disclosures can be found here.